Thread: MDF on door !!! ???

Originally Posted by Duke_Nukem

Hi All,

Ima novice when it comes to woodwork and i would like some info and your help on this :

I saw a nice old door design that i would like to try and recreate. the door itself is quite rough design and i m going to get the help of a professional carpenter to help me. iwill have him make the door Frame for me, so that its straight and strong and i willask him to make some grooves on the inside of the frame where i will be hopeully attaching an MDF panel (18mm) (it will be held in place by the 4 frames of the door.
on this MDF panel(175cm x 70cm) i will cut out a 85cm x 55 cm hole where i will attach a Glass...
i will make some moer pieces of wood to decorate it, but my worry is the MDF

Questions:
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1. is MDF strong enough to be used a s panel on a door (exterior door)

I wouldn't trust it for a single panel door. Might do for a 4 panel door just fine.

2. is MDF suitable for exterior use (i will paint it)

The short answer is NO.

3. How will it last in time ?

Not a good choice for exterior applications.

4. Can i use a sealer on the MDF and door wood, and then paint them to last longer?

Of course, but still not a good choice.

Please Help,

Thanks,

George

George,

I would see if you can find some MDO (medium density overlay), which is plywood with a fibre-impregnated outer covering. Paints like a dream, good for exterior applications, long lasting, and strong. (They use it for traffic signs).

Hi Bob,
i i will try and search for this MDO stuff, but dont know if we can get it here in Cyprus (Meditteranean Cyprus that is !!! )!!!

Thanks,

George

MDF is ok for interior use, like kitchen cabinet doors (even then it is best to use the moisture resistant kind, usually coloured green). I would never use it for an exterior door, even in a mediterranean environment.

cheers

George

DN,

I would go along with others comments about MDF not being suited to exterior use.

However, a number of years ago, sqatters broke through the glass in a 3 panel glazed back door at the home of my recently deceased uncle. As a stop gap repair, I removed the remnant glazing and retaing quad, and glued and screwed a panel of 18mm MDF in the opening. This was then given two coats of paint a couple of weeks later and is still in the door now, without deterioration.

I haven't replaced the door as yet as although we have renovated most of the house, the add on sunfoom where the door is located is a real bodge created by my uncle in three stages and is illegal, totally out of square, insuficient roof fall and scheduled for demolition and replacement next year. Door itself is rigged as a slider, the was from an 1860's house, and the frame opening is at least 2in out of square and the the frame is twisted as well. All in all not worth trying to fix all the problems so let the temp fix remain.

Door is under a verandah and facing east, so it gets mild morning sun and very little weather exposure. This has helped durability probably.

Could you get some thick tempered hardboard where you are, like weathertex?

BS, most modern solid outer doors are made from laminated MDF with a veneer covering them!( I have 2 friends who make them at a big name company)
Long as its sealed there is no problems using mdf... but a large single panel only 18mm thick is not strong enough. laminate two 16mm sheets together(its stronger than a single 32mm thickness and a whole lot cheaper).
Fully glue in the panel as the outer door frame is assembled, have the rebate in the frame at least 16mm square for good glue area. Rebate the panel to 16mm thick on the edges.
With the one I made last year I cut a chamfer all the way around leaving a 16mm edge thickness then I rebated it in 16mm to fit into the groove/rebate in the frame.(this gives it a raised panel look)
Dont let the panel float(unglued) as this is how water will enter and penetrate!

Make sure you prime it with at least 2 coats of heavy oil based pink primer, then 2~3 thick coats of high gloss enamel, you can paint the last coat in matt or low sheen if thats the finish you want.

Prob best to use HMR (High Moisture Resistance) MDF if you go that way.

hi All..

Thanks for your replies.

Iwill try and make the 'panel' out of strips of wood (jointed together) in the grooves of the frame and inside each other (sorry i dont know the woodworking term) .. I will search for the other materials you mention but i think i wont find them here in Cyprus.

Thanks again,

George

George, ensure you use a waterproof glue for long term durability, and take the possible expansion & contraction of the glued up panel when sizing it for the door.